Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH2

Evan B. Jochnowitz, Xu Zhang, Mark R. Nimlos, Mychel E. Varner, John F. Stanton, G. Barney Ellison

Research output: Contribution to journalArticlepeer-review

56 Scopus Citations

Abstract

The propargyl radical has twelve fundamental vibrational modes, r vib(HCCCH 2) = 5a 1 ⊕ 3b 1 ⊕ 4b 2, and nine have been detected in a cryogenic matrix. Ab initio coupled-cluster anharmonic force field calculations were used to help guide some of the assignments. The experimental HC=C-CH 2 matrix frequencies (cm -1) and polarizations are a 1 modes-3308.5 ±0.5, 3028.3 ±0.6, 1935.4 ±0.4, 1440.4 ±0.5, 1061.6 ±0.8; b 1 modes-686.6 ±0.4, 483.6 ±0.5; b 2 modes-1016.7 ±0.4, 620 ±2. We recommend a complete set of gas-phase vibrational frequencies for the propargyl radical, HC=C-CH 22B 1. From an analysis of the vibrational spectra, the small electric dipole moment, μd(HCCCH 2) = 0.150 D, and the large resonance energy (HCCCH 2), roughly 11 kcal mol -1, we conclude that propargyl is a completely delocalized hydrocarbon radical and is best written as HC=C-CH 2.

Original languageAmerican English
Pages (from-to)3812-3821
Number of pages10
JournalJournal of Physical Chemistry A
Volume109
Issue number17
DOIs
StatePublished - 5 May 2005

NREL Publication Number

  • NREL/JA-510-38403

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